The present invention relates to an illumination apparatus which is suitable for image pickup apparatuses and includes a reflective member reflecting light from a light source.
The above-described illumination apparatus is used, for example, as a flash unit for image pickup apparatuses such as digital cameras. The illumination apparatus includes an optical member such as a Fresnel lens which transmits light from the light source such as a discharge light emitting tube to control a light irradiation range, and a reflective member which reflects part of the light from the light source to return it to the light source and to introduce it to the optical member.
Japanese Patent No. 3544066 discloses an illumination apparatus including a reflective member in which its rear portion disposed on a rear side with respect to a center of a light source is formed into an elliptical shape whose focal point is located at the center of the light source, and its front portion disposed on a front side with respect to the center of the light source is formed into a cylindrical shape whose center is located at the center of the light source.
With miniaturization of the image pickup apparatus equipped with such an illumination apparatus, miniaturization of the illumination apparatus itself is also required.
However, the miniaturization of the illumination apparatus causes the light source and the front portion of the reflective member to be disposed closer to an optical member formed of optical plastic, which may melt the optical member by heat from the light source and the front portion of the reflective member. Moreover, in a case where a chassis of the image pickup apparatus is formed of metal, a creepage distance between the light source and the chassis reduces, which makes it easy to cause an electrical leak from the light source to the chassis.
Covering the light source and the reflective member by a heat-resistant optical member makes it possible to prevent the melting of the optical member and generation of the electrical leak. However, the optical member disperses light from the light source at a periphery of its light exit region, which may make it impossible to efficiently introduce the light to a required irradiation range.